Six Italian scientists and one government official are set to go to trial today in Italy (Sept. 20) on charges of manslaughter for not warning the public aggressively enough of an impending earthquake that killed more than 300 people in 2009.

While such a trial is unlikely on U.S. soil, experts say, American geologists and seismologists are watching closely, surprised at a legal system that would attempt to criminalize something as uncertain as earthquake prediction.

"Our ability to predict earthquake hazards is, frankly, lousy," said Seth Stein, a professor of Earth sciences at Northwestern University in Illinois. "Criminalizing something would only make sense if we really knew how to do this and someone did it wrong."

Henry Pollack, a professor of geology at the University of Michigan, echoed Stein's concerns.

"The whole thing seems bizarre to me," Pollack told LiveScience.

A deadly quake

The case has its roots in 2009, when a swarm of small earthquakes shook the central Italian region of Abruzzo in Italy. The region is seismically active, but knowing whether little shakes are leading up to a big temblor is impossible, seismologists say. A 1988 study of other quake-prone Italian regions found, for example, that about half of large quakes were preceded by weaker foreshocks. But only 2 percent of small quake swarms heralded a larger rupture. [See Photos of L'Aquila Earthquake Destruction]

Enzo Boschi, the then-president of Italy's National Institute of Geophysics and Volcanology and now a defendant in the case, seemed to allude to this uncertainty in a March 31, 2009, meeting in L'Aquila, a medieval city in Abruzzo. Comparing the situation to a large quake that struck L'Aquila in 1703, Boschi said, "It is unlikely that an earthquake like the one in 1703 could occur in the short term, but the possibility cannot be totally excluded."

In a press conference after the meeting, however, Department of Civil Protection official Bernardo De Bernardinis, also a defendant in the case, struck a more soothing tone, saying that the situation posed "no danger" and urging residents to relax.

Less than a week later, on April 6, a 6.3-magnitude quake struck in Abruzzo. L'Aquila's medieval buildings crumbled, killing 309 people and injuring more than 1,500.

Seismic uncertainty

The case against the scientists and De Bernardinis states that they did not do their duty in communicating risk to the citizens of L'Aquila and holds them responsible for manslaughter. A guilty verdict could carry up to 15 years in jail. The families of the dead are also seeking millions of dollars in civil damages.

But geoscientists say that asking the Italian scientists to predict when and where a quake might strike is like asking them to look into a cloudy crystal ball for an answer. [Natural Disasters: Top 10 U.S. Threats]

"I think that what people don't understand is just how low the risk was. These swarms of earthquakes do happen all the time," said John Vidale, a seismologist at the University of Washington. "We have swarms in my state, Washington, all the time, and I'm not sure of a single one that's ended with a large earthquake."

Although scientists — and cranks — have tried, there's no way to predict an earthquake days or weeks in advance. You'd have to fully understand the stresses deep in the Earth, Vidale told LiveScience, and you'd have to know exactly which parts of the crust are so weak that those stresses are going to cause ruptures.

"There are reasons to think that earthquakes just might not be predictable without knowing far more than we'll ever know about the stresses deep in the Earth," Vidale said.

Perhaps more surprisingly, even our understanding of what areas are at most risk of earthquakes is extremely limited, Northwestern's Stein told LiveScience. For example, no one expected that the section of fault that ruptured to cause Japan's horrific 9.1-magnitude Tohoku quake in March 2011 could result in a quake that large. The maximum was supposed to a magnitude 8, Stein said. Quakes are measured on a logarithmic scale, so a magnitude 9 quake has 10 times the amplitude and about 31 times more energy release than a magnitude 8, according to the U.S. Geological Survey (USGS).

The underestimate of the fault proved deadly, as Japanese seawalls were built under the assumption that extra-large quakes wouldn't produce any extra-large tsunamis. While a magnitude-8 quake might cause a 32-foot (10-meter) tsunami, Stein said, a magnitude-9 could cause a tsunami twice as tall. [Album: Monster Waves]

Japan is not the only spot that Earth's vibrations have been underestimated. Seismologists predicted less shaking in the 2010 Haiti earthquake than actually occurred. And a deadly magnitude-7.9 earthquake in Wenchaun, China, occurred in a spot previously rated as low-risk.

A big part of the problem, Stein said, is that the Earth moves on a different schedule than the human life span. Seismic records only stretch back 100 years, and human writing a few thousand years past that. Stein and his colleagues looked at the seismic records and more than 2,000 years of written records in northern China and found that, during that timeframe, no magnitude-7 or greater quake ever hit at the same place on a fault more than once.

"Every time there's a big earthquake, it's on an area that hasn't been active for 2,000 years," Stein said.

In other words, if Italian scientists are criminally liable for bad predictions, wouldn't all seismologists be just as criminal for their imperfect predictions?

"There's sort of a pattern here," Stein said. "Nobody knows how to do this very well. Countries have large programs to make hazards maps … these things are often big failures. Given that, the case for criminalizing it seems very small."

Could it happen here?

In the United States, the legal system would likely agree with Stein. According to Adam Kolber, a law professor at Brooklyn Law School, the Italian case would be very unlikely to go forward in the U.S.

First of all, for a manslaughter conviction, the experts would have to have what's called mens rea, Kolber told LiveScience. That means that they would have to be aware of a substantial and unjustifiable risk that their statements would cause someone's death.

"You have to find some particular person for whom if they were told there is a substantial risk of an earthquake that they would have left town or something like that, and that's going to be hard to show," Kolber said.

"To the extent that they're giving their scientific opinions, there's a First Amendment interest in protecting the speech," Kolber said.

Closing down science communication

Scientists contacted by LiveScience said they weren't personally concerned about prosecution for sharing their scientific opinions with the public, though some said they worried about a chilling effect on scientific openness in Italy.

"This is a very big pile of quicksand that will almost certainly tamp down any attempt to provide warnings about natural disasters," Michigan's Pollack told LiveScience.

The case does highlight the need to be upfront with the public about the limits of scientific predictions, said Erik Klemetti, a professor at Denison University in Ohio who specializes in volcanism and communicates with the public via his blog, Eruptions.

"Prediction of volcanic or earthquake hazards is not the game where you want to be going out and making bold, specific predictions, because we just really don't have the capability to do that," Klemetti said.

The case may take months to settle, and it remains to be seen whether Italy will hold scientists responsible for the deaths in L'Aquila. In the meantime, geoscientists are remaining humble about their understanding of tectonic forces.

"What you want to do in this business is to show humility in the face of the complexities of nature," Stein said. "I think that's probably a good thing for everybody to bear in mind."

Stephanie Pappas is a contributing writer for Live Science. She covers the world of human and animal behavior, as well as paleontology and other science topics. Stephanie has a Bachelor of Arts in psychology from the University of South Carolina and a graduate certificate in science communication from the University of California, Santa Cruz. She has ducked under a glacier in Switzerland and poked hot lava with a stick in Hawaii. Stephanie hails from East Tennessee, the global center for salamander diversity. Follow Stephanie on Google+.